1. Field of the Invention
The present invention is directed to a method and apparatus for inhalation anesthesia, and in particular to such a method and apparatus which permits re-use of anesthetic gases.
2. Description of the Prior Art
A patient respiration system is described in Swedish published application 459 155 wherein fresh respiration gas is mixed with an anesthetic from an anesthetic gasifier in a collecting line entering and departing the patient, and the exhalation gas from the patient passes through an adsorption filter. The anesthetic which is not absorbed by the patient is adsorbed by the adsorption filter, whereas the majority portion of the exhalation gas passes through the filter. During inhalation of the patient, the adsorbed anesthetic is desorbed from the adsorption material in the filter, and is re-supplied to the patient. It is unavoidable, however, that a slight amount of carbon dioxide from the exhalation gas of the patient is adsorbed in the adsorption material in the filter, and this will be subsequently desorbed and is re-supplied to the patient during the inhalation phase.